answering the obvious about holy Christian singleness

A short while ago I asked the obvious about holy Christian singleness: if sexual attraction is part of the basis for a good Christian marriage, yet all sexual attraction outside of marriage is unholy, how exactly can holy Christians ever end up married? After some research, I believe that I have an answer. It's fairly complex and nuanced, as reality often is. None of the following is a novel revelation; my aim is to lay out the ideas in a plain and forthright manner. Too frequently Christians speak in confounding half-truths and platitudes.

• "Sexual attraction", the single category I employed in the question, isn't helpful for morality. Instead there should be two categories: "lust" and "normal sex drive". Lust is the sin of a normal sex drive operating in immoral ways. So the upshot is that the holy task is to avoid lust, not normal sex drive. Actually any desire, such as craving for food, operating in an immoral way is "lust".
• Any person with normal sex drive could react biologically when presented with an exciting stimulus, just as any person with normal hunger could react biologically when presented with tasty food. This instantaneous perception and classification of an object isn't lust. It isn't even necessarily a full-fledged temptation. It's also unavoidable, because of the presence of a normal sex drive. The sole technique to avert it altogether is to withdraw every possible experience of stimuli. Christians would need to completely separate male from female! Regardless of marital status, clothing choices, and body shapes, adults in mixed groups simply must cope with this. In particular, unmarried Christians of opposite sexes can certainly get close enough to each other to have conversations and perform acts of service! It may seem strange to mention that permission, but I'm trying to walk through the topic comprehensively, step-by-step, omitting nothing.
• Lust starts to enter the situation after a normal sex drive makes its first recognition of someone other than the viewer's spouse. After that point, further thoughts might develop. These thoughts are temptations not only to carry out actions but to focus attention on mere contemplation of the actions. The initial thought is expressible in a statement like, "That person caught my eye", while the further thoughts are expressible in a statement like, "I want to do or think something". An object, for that is all that a person is at this primal level, is starting to lead to "plans". The stream of consciousness has begun to shift in an unlawful direction.
• I opine that lust is still not truly committed at this stage. I believe that lust isn't there until a decision is made. That is, the person must first realize that their mind is on a wrong track, and then intentionally not put a stop to it. Three clues of indulged lust: 1) a lingering or unbroken gaze, 2) a gaze that leaves momentarily only to return shortly thereafter for no other reason, 3) social interaction that's characterized by notable lack of eye contact. Rejection of the invitation to lust might not be as rapid as it could be. Doubtless it comes easier to some than others. Everyone can improve their skill with time and practice. The primary issue is whether or not someone does halt lust, not how soon they manage. Of course, assuming someone is serious and sincere, then a specific occurrence of lust shouldn't survive for any longer than perhaps 30 seconds.
• Unambiguous lust is the visualization of unlawful sexual action, where "action" refers to a broad range of activities: basically, whatever the lust entices the person to do to the visualized object. Unambiguous lust is the pursuit of ideas that excite a normal sex drive, outside of the lawful context of marriage. It might not be accompanied by physical acts. Pornography is one avenue. "Creative" daydreams could be a second. A third possibility doesn't receive as much comment: the nurtured desire to repeatedly see (and anticipate) someone other than one's spouse who tantalizes one's normal sex drive. To be sure, the experience could be comparatively mild; for example, it need not involve "explicit" imagining. However, it's a case of willingly-felt lust. Enjoying another person's "company" or "personality" isn't the same thing. Relatively subtle lust shows up in many little signs that aren't individually damning. Strangely deep disappointment when the object-person happens not to be in attendance. Unexplained tension during casual social interaction. An overeager tendency to exchange compliments. Excess attention at others' expense. A sensation like giddiness. If you'll allow me to illustrate... While I was a high school student, one of my teachers had a student assistant ("T.A.") for helping out with minor tasks. During that teacher's class, she was in the room, usually dressed immodestly but silently doing what the teacher assigned to her. We never talked. I don't recall a time when we had eye contact, in fact. Nevertheless, for a long time I grew accustomed to glancing at her many times during that class hour, almost automatically. I never invented sordid mental encounters. Was this lust? Well, I definitely wasn't looking at her for the sake of my education.
• All the preceding comments apply to unmarried Christians who are intrigued in gauging each other's suitability for forming a marriage. Meaning, Christians aren't temporarily allowed to lust in order to seek or evaluate candidate "mates". Lust isn't required. The rather unmistakable psychological "vote" of a normal sex drive establishes whether the other could fill that role in the marriage; no need to ponder or dwell on that. I've read that some Christians advocate a "friendship" phase - people must call each other "friends" for a while before one of them is permitted to raise the prospect of anything else. I'm not convinced. It's better for everyone to say their current intentions and then start out "slow", than to be "friends" and allow misinterpretation to slowly creep in to the growing emotions of one or both.
• Assuming reciprocal interest, the couple then spends time together to continue to learn and consider each other. Throughout this period between first attraction and marriage, they remain officially uncommitted and therefore unavailable for lust (or the actions that lust would motivate). This is a peculiar midway in which two people have appetites and cannot act out their impulses, despite being in close proximity. It's inherently unstable. The two either break apart or join in marriage. In the meantime, the suppression of lust isn't any different. Don't encourage it, kill it when it's there, don't fixate on it, and so forth. If the two aren't in total agreement, then one could accidentally or purposely tempt the other. Suggested guidelines aren't complicated, because the sex drive itself isn't complicated. A couple whose hypothetical end is marriage will already be partially driven by each other's nearness. Provocative clothing, private time as a pair, etc. increase the difficulty of preventing simple biology from taking over. 

In short, unmarried Christians who feel a mutual sexual attraction can surely result in a vibrant marriage, without committing the sin of lust along the way. But they must have the resolve and wisdom to see it through.